Motor operated valve analysis and testing system

ABSTRACT

A means of measuring the operating characteristics of a valve and its operator (16) and the corresponding imposed valve stem load is attached to the valve operator. The device provides a means of statically calibrating the operator relative to the imposed valve load and provides the means for recording traces of the imposed load and associated parameters and during dynamic conditions as related to the operation of the operator and valve combined. The device provides initial dynamic traces after initial assembly, maintenance and/or periodic testing of the operator and valve. The device is then used to provide diagnostic dynamic traces at any specified time in the future for the operator and valve. These future traces are used to compare with earlier traces to verify correct performance and most importantly to detect induced or impending damage, malfunctions, or maintenance requirements for the operator and valve.

BACKGROUND OF THE INVENTION

This invention generally relates to a system by which the overallperformance and actual thrust loads delivered by an electromechanical,mechanical, pneumatic or hydraulic valve operator can be statically anddynamically monitored.

The conditions giving rise to the problems solved by this invention arecommonly found in industries utilizing externally driven valves. Inparticular within the power industry, valves are operated remotely fromopen, closed and intermediate positions to improve or maintain utilitypower plant output, or in many cases provide for the protection of plantequipment, as well as protection of the general public from release ofradioactive materials either directly or indirectly. Continual properoperation of these valves is essential to industries and the generalpublic.

Typically these valves are required to operate under differing operatingconditions of temperature, pressure and flow within the commonrequirement for consistent operation. Further, the inherent operatingcharacteristics of the valve and operator are constantly undergoingmechanical or electrical changes from maintenance, repair, adjustments,calibration and wear.

In the earlier state-of-the-art, remote and local externally operatedvalves have been tested and calibrated to demonstrate that the operatorwill deliver the minimum or maximum thrust loads to the valve stem understatic conditions. The prior state-of-the-art did not provideverification that the static load delivered by the operator wasacceptable after field assembly or maintenance, nor did the prior artprovide any verification of the imposed valve load under dynamicconditions.

Historically, the thrust required to open or shut and subsequently toseat a valve was determined analytically by considering such factors astemperature, pressure, pressure drop, flow, liquid, valve type, packingload, motor voltage and valve mechanical characteristics. Once theminimum and maximum valve thrust requirements were determinedanalytically, the valve operator size could then be selected. Normally,motor operated valves in nuclear power plants, which perform a safetyfunction, are required to operate between seventy-five and onehundred-ten percent (75-110%) of nominal line voltage applied to theoperator. This requirement could lead to sizing of operator motors whichcan deliver from 1.0 to 2.5 times the required valve stem thrust,depending upon the actual line voltage. With oversized motors andoperators, the load imposed on the valve is typically much larger thananticipated or estimated by static means, due to the inherentmotor/operator inertia effects. Prior state-of-the-art methods forminimizing the effects of dynamic or inertia forces involved the use oftorque switches, motor brakes or compensating springs. Although thesedevices provided some relief, they do not preclude excessive orinadequate thrust loads being delivered to the valve stem, seat andbody. Complicating this situation is the fact that when a valve leaks,common practice has been to increase the force delivered to the valvestem through increased torque switch adjustments. Studies have shownthat this approach subsequently leads in many cases to irrevocabledamage to the valve or inoperativeness and more importantly degradationof system reliability as a whole.

The basic shortcoming of the prior art-load limiting devices is thatthey are not diagnostic in nature and, as in the the case of the torqueswitch, provide an element of protection which does not take intoaccount the dynamic considerations of the valve and operator duringactual operation. Changing effects on valve load under dynamicconditions such as line voltage, packing tightness, gear train wear,lubrication degradation, calibration, and adjustment errors cannot beidentified with the earlier state of the art devices. Further, in mostcases, prior state of the art post-maintenance valve and operatoractuation testing will not identify progressive degradation of valveperformance.

A SUMMARY OF THE INVENTION

Briefly described, the present invention comprises a modification to theprior state of the art, which includes the addition of a device(s) whichwill measure motion of the operator drive system continuously andprovide a dynamic trace of the actual load being delivered to the valvethroughout the operation cycle. After initial calibration, the recordedtrace will provide accurate information upon which more accurate andappropriate load limiting device adjustments can be made. In doing so,increased system reliability and reduced probability of physical valvedamage can be obtained. This improvement over the state-of-the-art alsoprovides a means to determine, monitor and test valve and operatorperformance throughout its cycle, from open to closed positions and viceversa. Information on valve performance, which heretofore, wasunavailable from the previous state-of-the-art protection devices, willprovide a direct indication of developing valve and operator problemssuch as excessive or inadequate packing load, excessive inertia,proximity to premature tripping, incorrectly set operating limit andtorque switches, improperly functioning thermal overload devices,inadequate or excessive stem thrust loads, gear train wear, stem damage,and load relaxation. All of the above forms of valve and/or operatordegradation will be apparent from data records obtained from load,current, and continuity devices, which form part of the total analysisand testing hardware of the invention, described in more detail tofollow. Knowledge of the above actual or pending problems will enablethe user to take necessary corrective action prior to actual failure ofthe valve, to perform its intended function. Early corrective actioncan, therefore, lead to improved system reliability, improved safety,lower maintenance, and repair costs.

The user, of the present invention, will have the capability of testingand monitoring the valve and operator performance remotely, which willreduce personnel radiation exposures in nuclear power plants.Furthermore, the present invention will be of great value to otherindustry applications such as chemical or hazardous materialenvironments or even to those applications where accessibility to thosecomponents is restricted.

The purpose of the present invention, when taken as a whole, is toprovide a method by which the general material and operational conditionof a valve and its associated operator can be determined and evaluated.

One object of the present invention is to provide an actual dynamicvalve operator spring pack movement-time trace.

Another object of the invention is to correlate valve stem load tospring pack movement, and therefore provide a valve stem load-timetrace.

Another object of the invention is to provide an operator motorcurrent-time trace that can be correlated with the valve stem loadtrace.

Another object of the invention is to provide a torque and limit switchon/off-time trace that can be correlated with the valve stem load andmotor current traces.

According to one aspect of the invention there is a diagnosticinterrelationship between the calibrated valve stem load-time trace, themotor current-time trace, and the torque and limit switch position-timetrace.

According to another aspect of the invention the interrelationship ofthe stem load-time trace, motor current-time trace, and the torque andlimit switch position-time trace can be used to verify correct valvestem loads for initial valve and operator installations, or futureoperational testing of the valve and operator.

An alternate embodiment of the present invention includes a speciallydesigned spring pack movement device to facilitate mounting of thedevice to the valve operator housing to allow installation and operationof the device in congested areas.

Other objects, features and advantages of the present invention willbecome apparent upon reading and understanding this specification whentaken in conjuntion with the accompanying drawings.

A BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1: A pictoral, partial view of one embodiment of a valve, valveoperator, and piping system in accordance with the present invention.

FIG. 2: A cut-away view of a valve operator showing the motor, worm,worm gear, and spring pack arrangement in accordance with the presentinvention.

FIG. 3: A cut-away view of a valve operator showing the motor, worm,worm gear, and spring pack arrangement, in accordance with the presentinvention, showing an alternate embodiment to that of FIG. 2.

FIG. 4: A cut-away view of a valve analysis and testing system, showingthe valve operator of FIG. 2, with the attached stem load calibrationdevice and spring pack movement device in accordance with the presentinvention.

FIG. 5: A schematic representation of a valve analysis and testingsystem in accordance with the present invention, showing a valveoperator with attached diagnostic devices, recording device, andrecorded function-time parameters.

FIG. 6: A cut-away view, taken along line 6--6 of FIG. 5, showing thespring movement device, and related components, in accordance with thepresent invention.

FIG. 7: A cut-away view, taken along line 7--7 of FIG. 5, showing thespring movement device, and related components, in accordance with thepresent invention.

FIG. 8: An electrical schematic showing of the design of the switchposition indicating circuitry and sub-components, in accordance with thepresent invention.

FIG. 8A: A sample trace from the magnetic coil of the limit/torqueswitch position device, in accordance with the present invention.

FIG. 9: An electrical block diagram showing how the system signals areobtained and processed, in accordance with the present invention.

A DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now in greater detail to the drawings, in which like numeralsrepresent like components throughout the different views, FIG. 1 showsthe environment in which the preferred embodiment of the invention isused. A process pipe 14, having a valve 15, with an attached operator 16is within an operating system with a prescribed flow, pressure, andtemperature. The valve 15 is opened or closed as required for systemcontrol, and is opened or closed by the operator 16. The operator 16 canbe electromenchanical, mechanical, pneumatic, or hydraulic.

FIGS. 2 and 3 show two embodiments of operators 16, 16' used in thepresent invention. The components of the two FIGS. 2 and 3 are similaralthough differently arranged. The operators 16, 16' are similar tooperator and valve stem arrangements typically used in the art. Themotor 1 drives a worm shaft 2, which in turn drives a worm 3, which inturn drives a worm gear 4, which in turn drives the valve stem 5, toopen or close the valve 15. A reactor device to the actual stem thrustand inertia of the motor and other operator components is shown as acluster of compression springs or spring pack 7 provided at one end ofthe worm shaft 2, as shown in FIGS. 2 and 3. When the valve 15 closes oropens, the valve stem 5 will abruptly stop and even though the currentto the motor 1 is interrupted, the rotational and kinetic energy of thesystem will cause the worm gear 4 to induce additional loads on thevalve stem 5. In order to absorb some of this energy, the spring pack 7is provided and is compressed by the worm shaft 2 as the inertia of thesystem attempts to move the valve stem 5.

FIG. 5 shows a stem load calibration device 17, and a spring packmovement device 8, which are used to calibrate the spring pack 7movement relative to the imposed load on the valve stem 5. Thiscalibration and correlation is accomplished by a simultaneous inducementof a load into the operator through the worm shaft 2 and tracing theactual stem 5 load and spring pack 7 movement through the use of acalibrated load cell 9 and linear velocity differential transducer(LVDT) 30.

SPRING PACK MOVEMENT DEVICE 8

The Spring Pack Movement Device 8 is shown in detail in FIGS. 6 and 7.Its function is to monitor both statically and dynamically the linearmotion of the operator spring pack 7. FIGS. 6 and 7 show the significantcomponents and operation of the spring pack movement device 8. Withreference to FIGS. 1, 4, 5, 6, and 7, the spring pack movement device 8and attached mounting bracket 21 is bolted directly onto the spring packhousing 35, which is an integral part of the operator 16. The extensionrod 22 is pressed against the spring pack 7 by the tension systemconsisting of the small diameter wire 23, attached to the extension rod22, the LVDT core 24 attached to the wire 23, wire 25, and the spring26. The tension system including the spring 26 force is designed suchthat the rapid movement of a given spring pack 7 does not produceinertia forces in the tension system that would allow separation of theextension rod 22 and spring pack 7. The LVDT core 24 is mounted in acommercially available linear voltage differential transducer 30, whichis supported by bracket 31. The drum wheels 27, 28, and 29 are used, andso located, to convert the translation of the extension rod 22 intoaxial movement of the LVDT core 24, inside the LVDT 30. Thus, the springpack 7 movement is traced electronically and this movement is displayedon an analytical device such as an Oscilloscope 10a (FIG. 5),hereinafter known generally as the recorder 10a.

STEM LOAD CALIBRATION DEVICE--17

The purpose of this the Stem Load Calibration Device 17 is to initiallycorrelate the movement of the spring pack 7 to the actual load beingdelivered to a valve stem 5. Stem load can be calibrated to lineardisplacement of the spring pack 7 since one is merely a reaction to theother. The calibration device 17 is a structure, preferably of steel,comprised of mulltiple support rods 6 and a drilled flat circular plate20. On the underside of the plate is fastened a calibrated load cell 9,which is a well known device in the state-of-the-art. The calibrationdevice 17 sits above the valve operator body 16. When an extension shaft34 is then placed between the lower surface of the load cell 9 and theupper valve stem 5 surface, a load can be induced on the stem 5 byinputing torque via the worm shaft 2.

CHANNEL SELECTOR AND SIGNAL CONDITIONER DEVICE--10

The purpose of the Channel Selector and Signal Conditioner Device 10 isas follows: (Refer to FIG. 5.)

1. Provide a conditioned power supply for the LVDT of the spring packmovement device 8, for load cell 9 and torque/limit switch positionindicating device 18.

2. House the electronic circuitry (see FIG. 8) for the detection of thelimit and torque switch position. This circuit will be discussed in moredetail to follow.

3. Provide the necessary sub-components for switching capabilities toenable the user to output any of the following signals to the datacollection system; spring pack movement, load cell, motor current, andtorque/limit control circuit switch position.

4. Provide input and output connections for an external motor currentmeasuring device 11.

5. Provide local digital readout capabilities for the load cell 9 andspring pack movement device 8.

6. Provide a load cell 9 calibration circuit and output signal forverifying proper operation of the recording device 10a.

LIMIT/TORQUE SWITCH POSITION DEVICE--18

The limit/torque switch position device 18 comprises a sensing circuitand associated electronics which are housed in the Channel Selector andConditioning Device 10. As can be seen from the electrical schematicdiagram, FIG. 8, the circuit will provide a varying output to therecording device 10a depending on which of the switches (Limit 33, orTorque 32) are closed or opened. It should be noted that if valve 15 isbeing operated, only one of the contacts identified as MC or MO (FIG. 8)will be closed, depending on whether the valve is being opened orclosed. A sample trace from the magnetic coil 45 is shown in FIG. 8A forease of understanding. Note that the variable output shown in the sampletrace is obtained by looping the signal wire from one side of theparallel control circuit around the magnetic coil more times than thesignal wire from the other parallel path. The result of this embodimentof the invention is an output to the recording device 10a, whosemagnitude is reflective of which of the two parallel paths, or both, hasits associated switches opened or closed.

CURRENT MEASURING DEVICE-- 11 The Current Measuring Device 11 is used tomonitor the current draw of the valve operator motor 1 during theoperation of the valve 15. The power required to operate valve 15 can bedirectly correlated to the actual delivered stem thrust of the operator16, and thus, corresponding traces (curves) for the stem load 13 andmotor current 12 will be obtained. By initial comparison of the twocurves 12 and 13, the user can subsequently obtain either one of thesignature traces 12 or 13, and have sufficient information on theperformance of the valve/operator assembly. The desirability of thecurrent signature traces 12 lies in the fact that it is generally easierto obtain than the stem load curve 13. The component which is preferablyused to obtain the motor current trace 12 is a clamp-on Ampmeter 11which is well known to those familiar with the state-of-the-art. Thesignal output of the motor current measuring device 11 is sent to theChannel Selector and Conditioning Device 10 which has been describedpreviously. RECORDER--10a

The Recorder 10a is intended to acquire and store the input data forsubsequent display on a screen, or hardcopy printer, for analysis and/orrecord purposes. Typical recording devices 10a used for the abovepurposes are well known to those familiar with the state-of-the-art.

The interrelationship of the above described components of the preferredembodiment of the valve analysis and testing system of the presentinvention is shown in FIG. 5.

An electrical block diagram of the invention is provided as FIG. 9, toshow how the electrical signals are obtained and processed by each ofcomponent parts, also, referred to as component sub-systems.

Referring to FIG. 5 and having established the valve stem 5 load andspring pack 7 movement relationship and connecting the spring packmovement device 8 to the channel selector and conditioning device 10,the spring pack 7 movement (which is indicative of actual stem load) asa function of time can be recorded as a stem load trace 13 for anyoperation cycle of the valve. In addition, the motor current measuringdevice 11 is given to provide a current trace 12, and can be correlatedto the stem load trace 13 for further operator and valve performanceevaluation, as defined later.

As seen in FIGS. 4 and 5, the valve operator 16 includes a torque switch32 and limit switch 33 (located within the indicated housing, but notseen here), which are connected and function in a manner known in theart. A torque/limit switch position indication device 18 is electricallywired into the torque switch 32 and limit switch 33 control circuit, asshown in FIG. 8. The output from the torque/limit switch position device18 is connected to the recording device 10a, via the channel selectorand conditioning device 10, which in turn provides a switch on-off-timetrace 19, also called torque/limit switch position-time trace 19, forthe duration of the operator cycle.

When the spring pack measuring device 8, motor current measuring device11, and the torque/limit switch position indication device 18 areactivated simultaneously and recordings of each, with reference to thesame operator cycle-time, are obtained the relationship of therecordings provide diagnostic data. To be more specific, since thespring pack 7 movement is calibrated to the valve stem 5 load, thespring pack movement trace is a direct dynamic stem load-timerelationship for an operator cycle. Thus, the spring pack tracecorresponds to actual stem load. As a result of the correlation, thestem load trace 13 is also a spring pack movement trace 13 and will beused interchangeably in subsequently describing the invention. Thecurrent measuring device 11 measures the current required by theoperator motor to deliver the stem load and, therefore, the current-timetrace 12 is also a record of the valve stem load-time relationship. Inaddition, the torque/limit switch indicating device 18 provides a switchposition indication for the torque and limit switches 32 and 33,therefore the torque/limit switch position-time trace 19 provides adirect indication of the torque and limit switch timing relationship.Most important is that the torque and limit switch "off" indication canbe compared to the stem load trace 13 to establish the additional stemloads delivered to the stem by the inertia of the motor and operator 16,after the torque and limit switches 32 and 33, have interrupted thecurrent to the motor. It is recognized that the stem load trace 13 is adirect record of the dynamic valve stem load during the valve operatorcycle, and therefore provides confirmation of the actual load imposed onthe valve stem 5. If the recorded stem load is less than, or greaterthan, that required for proper valve operation, the traces 12, 13 and15, are compared and the comparisons are used to readjust the torqueswitch 32 and/or limit 33 switch settings, and therefore the stem loadto within required limits.

Further a spring pack movement or stem load trace 13, current trace 12,and switch position trace 19, generated from a properly functioningvalve and operator combination, can be used as a data base forcomparison of subsequent spring pack movement, current and switchposition indication traces for purposes of verification of performance,or as a means of detecting improper functioning components of the valve15 and operator 16.

In preferred embodiments, the proces of comparison and analysis of thedata is accomplished through the use of computer data bases andspecialized programs which calculate and compare critical valve 15 andoperator 16 parameters. This historical comparison identifies to theuser a slowly degrading condition, which heretofore could not be readilydetected between sequential test frequencies.

Typical valve and operator parameters which are determined and comparedfrom the dynamic traces 12, 13 and 19 are as follows:

A. Stem load versus spring pack 7 deflection. Correlation of these twoparameters provides the user with a known stem load for a given,subsequently obtained, spring pack movement.

B. Valve packing load changes.

C. Starting stem load to initially move the valve from its closed oropen position, commonly known in the state-of-the-art as hammer blow.

D. Total stem load, which is the final observed stem load at the end ofa given valve cycle.

E. Available stem load to seat a valve. This load is the differencebetween the packing and and total stem load.

F. Stem load at which the torque or limit switches actuate. Thisprovides information on the overall operational set-up of a valve andoperator control circuitry.

G. Total time for the valve to open or close.

H. General condition of the operator mechanical gearing and stem, byanalysis of the valve mid-cycle stem load trace 13.

I. Average motor current requirements, which if it changes, can providean indication of degrading valve performance.

An example of a computer program, which is part of the invention toperform the above analytical manipulations, is shown following:

This is an example computer program for analysis of motor operated valvespring pack 7 movement, motor current (at current measuring device 11)and torque/limit switch 32 and 33 activation. This program is writtenfor the Norland 3000 DMX computer. Program listing:

    ______________________________________                                        1.       Display B C C' D E' RO DPLY                                          2.       O > B                                                                3.       O > C                                                                4.       O > C'                                                               5.       O > D                                                                6.       O > E'                                                               7.       O > RO                                                               8.       PAUS                                                                 9.       PAUS                                                                 10.      O IF > RI                                                            11.      D DISK 101                                                           12.      D DISK 102                                                           13.      D DISK 103                                                           14.      D DISK 104                                                           15.      D DISK 105                                                           16.      D DISK 106                                                           17.      D DISK 107                                                           18.      D DISK 108                                                           19.      D DISK 109                                                           20.      D DISK 110                                                           21.      D DISK 111                                                           22.      D DISK 112                                                           23.      D DISK 113                                                           24.      D DISK 114                                                           25.      END                                                                  26.      PAUS                                                                 27.      PAUS                                                                 28.      DPLY A > DISK 104                                                    29.      DISK 104 LBL DATE LBL                                                30.      DPLY A' > DISK 105                                                   31.      DISK 105 LBL TIME LBL                                                32.      DPLY D' > DISK 111                                                   33.      DISK 111 LBL LOAD CONV LBL                                           34.      PAUS                                                                 35.      PAUS                                                                 36.      DPLY Q1 > DISK 101                                                   37.      DISK 101 LBL Q1 CURVE LBL                                            38.      DPLY Q2 > DISK 102                                                   39.      DISK 102 LBL Q2 CURVE LBL                                            40.      DPLY Q3 > DISK 103                                                   41.      DISK 103 LBL Q2 CURVE LBL                                            42.      PAUS                                                                 43.      PAUS                                                                 44.      RMS > C'                                                             45.      COOR                                                                 46.      C' > R8                                                              47.      O IF > V                                                             48.      O IF > V'                                                            49.      C' * -1 > C'                                                         50.      GOTO 61                                                              51.      END                                                                  52.      GOTO 119                                                             53.      END                                                                  54.      O IF > V'                                                            55.      O IF > V                                                             56.      C' * -1 > C'                                                         57.      GOTO 61                                                              58.      END                                                                  59.      GOTO 119                                                             60.      END                                                                  61.      PAUS                                                                 62.      PAUS                                                                 63.      COOR                                                                 64.      H' -H > D                                                            65.      PAUS                                                                 66.      PAUS                                                                 67.      COOR                                                                 68.      C' -V > E                                                            69.      E * D' > E                                                           70.      PAUS                                                                 71.      PAUS                                                                 72.      COOR                                                                 73.      V' -V > C                                                            74.      C * D' > C                                                           75.      PAUS                                                                 76.      PAUS                                                                 77.      RMS > B'                                                             78.      B' > R9                                                              79.      COOR                                                                 80.      O IF > V                                                             81.      O IF > V'                                                            82.      B' * -1 > B'                                                         83.      GOTO 94                                                              84.      END                                                                  85.      GOTO 119                                                             86.      END                                                                  87.      O IF > V'                                                            88.      O IF > V                                                             89.      B' * -1 > B'                                                         90.      GOTO 94                                                              91.      END                                                                  92.      GOTO 119                                                             93.      END                                                                  94.      B' * D' > B                                                          95.      R9-R8 > RO                                                           96.      RO * D' >RO                                                          97.      PAUS                                                                 98.      PAUS                                                                 99.      COOR                                                                 100.     C' -V > E'                                                           101.     E' * D' > E'                                                         102.     C' * D' > C'                                                         103.     DPLY B > DISK 106                                                    104.     DISK 106 LABL RUNNG UBS LABL                                         105.     DPLY B' > DISK 107                                                   106.     DISK 107 LABL RUNNG V LABL                                           107.     DPLY C > DISK 108                                                    108.     DISK 108 LABL AVA THRST LABL                                         109.     DPLY C' > DISK 109                                                   110.     DISK 109 LABL PRE HB RMS LABL                                        111.     DPLY D > DISK 110                                                    112.     DISK 110 LABL TIME O/C LABL                                          113.     DPLY E > DISK 112                                                    114.     DISK 112 LABL PKHB/RMS LABL                                          115.     DPLY E' > DISK 113                                                   116.     DISK 113 LABL TTL THRST LABL                                         117.     DPLY RO > DISK 114                                                   118.     DISK 114 LABL DKNG LD LABL                                           119.     END                                                                  ______________________________________                                    

Although only the preferred embodiment of the invention has beendescribed, it is evident that the invention will find uses other thanelectric motor operated valves. For example, the invention is useful forverifying correct operation of manual, hydraulic, and pneumatic actuatedvalves.

Whereas, this invention has been described in detail with particularreference to preferred embodiments thereof, it will be understood thatvariations and modifications can be effected within the spirit and scopeof the invention, as described before and as defined in the appendedclaims.

What is claimed is as follows:
 1. In combination, a valve operatorincluding a movable valve stem and a worm, driven by a motor and aspring means for reacting to stem thrust, and a torque/limit switchmeans for indicating when the worm has developed a predetermined load,said torque/limit switch means being a switch means comprised of torqueand limit switches, a valve stem load calibration device, said valvestem load calibration device being a device that allows for measuringthe load on said valve stem, said spring means comprising a cluster ofcompression springs hereinafter called a spring pack, a spring packmovement monitoring device, a motor current measuring device, a torqueand a limit switch position indication device for indicating thepositions of each switch in said torque/limit switch means, and acorrelating and recording device for providing an interrelated timerelationship of valve operator parameters, said parameters comprisingthose determined by the aforesaid indicating, measuring and monitoringdevices, of which parameters are used as a verification and diagnostictool to determine the operating characteristics of the valve operatorand the imposed load on the valve stem.
 2. The combination of claim 1,wherein the valve stem load calibration device is attached directly tothe valve stem and is correlated directly with the spring pack movement.3. The combination of claim 1, wherein the operator spring pack movementmonitoring device records the spring movement and is correlated to thecorresponding valve stem load.
 4. The combination of claims 1 or 3,wherein the motor current measuring device records the motor currentrequired to operate the valve and is correlated to the valve stem load.5. The combination of claim 4, wherein the torque and limit switchindication device records the on/off positions and is correlated to themotor current and valve stem load traces.
 6. The combination of claims 1or 5, wherein the recorded results of the spring pack movementmonitoring device, motor current measuring device, and the torque andlimit switch position indication device are used as a documental recordof valve and operator performance characteristics, and are used asfuture comparisons for records obtained from the same valve and operatorto verify operating performance, and the time relationship of therecords are used to correct and adjust the operator, if the operatingcharacteristics are not within required limits.